The Applicant is aware of U.S. Pat. Nos. 4,382,787, 4,449,930, 4,533,323 and 4,548,581 as well as U.S. Pat. Nos. Des. 286,179 and 286,436, all to Huffman. These patents and design patents describe and illustrate various embodiments of dental model articulators. All of the articulators described and illustrated in these patents and design patents comprise a pair of substantially U-shaped brackets which have their limbs pivotally interconnected. In some of the illustrated embodiments, the limbs of the U-shaped brackets are interconnected, snap-fit fashion. Substantially spherical members are formed integrally with crosspieces of each of the U-shaped brackets. A mounting member is provided for attachment to each cast. Each mounting member defines a socket in a rear portion thereof within which the spherical member of one of the brackets fits to form a ball and socket joint.
It is a problem with this type of arrangement, that two adhesive bonds have to be formed for each cast, ie. bonding of the mounting member to the cast, and the bonding of the spherical member in the socket. While waiting for these adhesive bonds to set, the casts together with the articulator, have to be held and due to the use of the two adhesive bonds for each cast, the likelihood of the position of the articulator relative to the casts moving during the setting of the adhesive bonds is increased. Also, with the provision of the snap-fit type interconnection between the limbs of the brackets, lateral movement, without these snap-fit interconnections coming apart, is limited.
The Applicant is further aware of apparatus for locating a cast of a set of upper teeth and a cast of a set of lower teeth of a dental model in an operative configuration which simulates the relative position of the upper and lower sets of teeth of a person, which comprises a retort stand type arrangement having two vertically spaced, horizontally extending arms which are releasably clamped to a vertical bar of the retort stand. The arms are articulated to be pivotal in a vertical plane. With this arrangement, the two casts of the model are initially waxed together, and then are cemented to the respective free ends of the arms eg. by using Plaster of Paris. Once the cement has set, the two casts of the model, still waxed together and with the arms attached, are released from the retort stand. The two casts are then separated from each other by removing the wax. Finally the arms are again clamped to the stand and the pivotal opening and closing movement of a person's jaws can be simulated by pivoting the arms relative to each other. It will be appreciated that this is a time consuming an somewhat messy process and a technician usually requires assistance, albeit unskilled assistance to carry it out. Also, with this type of apparatus only pivotal movement of a person's jaw can be simulated, ie. no lateral movement of the jaw can be simulated.